#1619 chore: Simplify native CLI installer command construction

Summary

• Preserve native CLI installer behavior while separating command construction from process and path responsibilities.
• Keep the existing public installer command API unchanged.

User Impact

• No user-visible behavior change.
• Setup and uninstall continue to produce the same executable names, arguments, manual commands, release tags, and installer script URLs.

Changes

• Move install command construction and quoting helpers into NativeCliCommandBuilder.
• Keep NativeCliInstaller.GetInstallCommand as the public facade.
• Keep uninstall path resolution in NativeCliInstaller until the path responsibility is split separately.
• Retarget command-focused tests and the overload guard to the extracted builder; the guard still reports missing targets.

Verification

• Unity compile: 0 errors, 0 warnings
• NativeCliInstallerTests: 32 passed
• StaticFacadeStateGuardTests: 20 passed
• CliSetupApplicationServiceTests: 4 passed
• git diff --check
• No IPC or protocol changes